President Trump fired FBI director James Comey, who had made himself eminently fireable. Last July, Comey took it upon himself to become not only the nation’s top policeman, but its top prosecutor, explaining in a long press conference that while Hillary Clinton had clearly broken the law by hosting classified information on her private e-mail server, she did not deserve to be prosecuted — a decision that was not his to make. Then, shortly before November’s election, Comey announced that the FBI was reopening its investigation into Clinton’s e-mails, based on evidence found on the computer of Anthony Weiner. A few days later, he reclosed the reopened investigation. This sequence of events — which has had Republicans and Democrats repeatedly reversing themselves in their opinions of Comey — was outlined in a memo by Deputy Attorney General Rod J. Rosenstein, who rightly observed that Comey’s actions broke with longstanding Justice Department precedent, to the frustration of critics on both sides. Indeed, the Bureau’s reputation is at a low ebb because of Comey’s decisions, and one way or the other, he needed to go. Of course, press reports suggest that when Trump fired Comey, he was angry about the Russia probe, Comey’s ubiquity in the media, and the FBI director’s refusal to make a statement exonerating him of wrongdoing. If true, none of this speaks well of Trump. The public deserves a forthright answer about the hows and whys of the decision, and if the White House does not provide it, Congress must seek it. Ideally, the administration will find a replacement well respected on both sides of the aisle who will be appropriately independent of the position’s inevitable political pressures.